Rock drilling apparatus



Feb. 16, 1965 A. P. c. STENUICK ROCK DRILLING APPARATUS Filed July 3,1961 Inventor Funk! Pie/(1! (34 111.15 STENLHCK jbore hole. f v t t pThe requisitecompressedair is conveniently suppliedto the said hammerfrom a suitable compressor through United States Patent 3,169,584- ROCKDRILLING APPARATUS Andre Pierre Cmlle Stenuick, Fontaine IEveque, Belgium, assignor to Halifax Tool Company Limited, Halifax, England, aBritish company p Filed July 3, 1%1, Ser. No. 121,626 7 Claimspriority,application Great Britain, July 7, 1960,

7 Claims. (Cl. 173-18) This invention concerns a pneumatically operatedpercussive hammer for rock drilling or like boring apparatus or rigs,such harnme-r being of the kind (hereinafter re ferred' to as the kindspecified) comprising a cylinder having at its operative end a part orchuck (hereinafter called a fchuc adapted to receive the shank of a bitaxially reciprocable in said chuck to an extent limited by retainingmeans (c.g. a retaining ring, pin or key) and the inner end of which bitis adapted to be struck repeated 1 blows by a piston located within saidcylinder and reciprocable axially therein by compressed air alternatelyapplied to opposite ends'ot" the piston under the control of adistributor; ValVe located" in a valve'chest disposed'towards that endof the cylinder remote from the said chuck,

said distributor valve controlling at least two ports or sets or ports,one for supplying compressed air to one end of said piston and the otherfor'supplyingcompressed air i to theotherend of the'piston and thedistributo'r valve being adapted to close these ports or sets' of. portsalternately automatically as the said piston recipr'ocates in thecylinder- 0f thehamrner and opens one; or-more exhaust ports alternatelytothe opposite-ends of the piston.

It is desirable-when using ahammer ofth'e type speeified to lead air,e.g. exhaust air'or live an or'fboth, under pressure continuously orpulsatingly to the'bit-end oi the hammer for discharge intoabore helebeing drilled thereby to' keep cuttings Qtflflbl'iS (hereinafter calleddebris). clear of the bit to discharge it from the appropriate conduit'tneans which may include one or 5 more 'drill'tubes'by which thehammer-is carried.

The' i nvention isespecially applicable'to down-the-hole equipment ofthe form described in U,S. l atent 7N twe -j a I v 1 j The saidretaining means permits an' axial movement of V the bit in its chuckconsiderably g reater thamthebit makes in normal operation, aniwhen'apneumatically operated percussivelhammer of the kindlspecifiedis innormal use, the resultant reaction thrust of the ground onwhich the bitis acting plus the forward ordownwmd thrust .ofthe hammerpmaintains thebit in P IOp errelaof the hammer which it wouldflnot ordinarily strike:this 1 Will particularlyfbe the case where the hammer has been in usefor some time and somejdegr'ee of wear has taken place whereby air,which would otherwise form a cushion to retard the latter portion of theadvance movement of the piston, mayescape. Thus where the piston is, asit usually will be, furnished at the: head of a shank'which is guided inan internal bushrwithin the cylinder, the

1 head of the pistoniwill fbe liable to strike the inner end of the bushand damage the same;

Patented Feb. 16,1965

The same sort of trouble may also arise should a substantial cavity inthe rock or ground he met during the drilling operation (particularly inthe case of vertical drilling). so that the hammer meets no resistanceand tends to advance, and so that the bit advances freely from the chuckuntil it is stopped by the said retaining means.

Furthermore where the hammer is withdrawn orj'lifted' or a cavity is metas aforesaid, there is a tendency, due to vibration, for the bit tobounce about so that it'may' be struck occasionalblows by thereciprocating piston which will drive the bit against the bit retainingmeans (e.gv the'ret'aining ring, pin or key) and cause'f-ailure' of 7this part with the consequential loss of the bit down the hole. a r a Itis an object of this invention to provide, ina pneumatically operatedpercussive hammer of thekind spec ified, means for automaticallyarresting the reciprocation of the hammer piston should the normalthruston the 7 bit be relieved and the bit be permitted to move, freelyforwardly relatively to the chuck of the. hammer to anextent greaterthan that whichis customary in the normal functioning of the hammer. i iAccording to this invention there is provided a pneu matically operatedpercussive hammer for rock drilling or like boring apparatus and of thekind specified, such hammer including "by-pass valve' means forthy-passing compressed air past the distributor valve of the hammer toonetend of the cylinderof the latter, and means adapted automatically toopen said by-pass valve means so that compressed air will automaticallybe supplied to or predominantly to one end of the said hammer piston soas to retain such piston ,at oneend of the said cylinder and againstreciprocation in such cylindenwheneyer the bit of the hammer is, du ing.ope-ration, relieved of the normal resultant thrust thereon and'imtilnoinialoperating conditions are restored." i r The bit will usually berelievedof the normalresultant thrust during the operation of the"hammer if the latter is withdrawn or lifted with respect to, a borehole ori'if the hau'unerencounters a cavity duringthe-drillingloperation. v I Should abnormal conditions such as abovereferred to arise during normal workingoperations and it should thusbecome necessary automatically to arrest the reciprocation of thehammerpiston, it is very desirable that the supply of air under pressureto the bit-end of the hammer for discharging debris from'the bore holeshould nevertheless be maintained in order to preventthe debris fall ingback into the bore hole and causing alblockage;

Therefore, accordingto a further to ature of the invention, provision'ismade whereby even'when the 'compressed air supplied to the hammer isby-p'assed primarily'to one end of the, hammer piston to retain itin-fan end position against reciprocatiom some compressed'air willalso'bef hammer for debris clearing delivered to the bit-end of thepurposes. t

Preferably his tothe back-end '(ie. the end remote tne bit) of't'hehammer-piston to which. the said f by-passed compressed air is suppliedsoQthat the piston The invention is especially applicablc 'to'apneumatically operated percussive hammer of the specifiedfandin .which ashock absorber piston is provided c'oaxially in,

or coaxial with, that end of the hammer cylinderremote from thebitl-andfor axialsliding movementw'ith respect V to such cylinder, thesaid" valve chest thus, being located between the shock absorber pistonand the hammer piston and the shock absorber piston having port meansthrough whichfcompressed air may be supplied to the valve chest,

preferably via a non-return or check valve independent, 1 1 r of thedistributor valve, said shock absorber pistonbeing adapted-,- when thehammr'isi in use; for attachment to will be. maintained in its advanced.position by sucli aii the leading end ofthe said drill tube or tubes bywhich the hammer is carried.

According to a further feature of the invention, where the hammer isfurnished with a shock absorber piston as above described, the saidby-pass valve may be so associated therewiththat, on relative axialwithdrawal movement taking place between the shock absorber piston andthe hammer cylinder due to the initiation of the withdrawal of-the drilltubes immediately preparatory to the withdrawal of the hammer from thebore hole, or due to the uncontrolled advancement or falling of thehammer due to it meeting a cavity during drilling, the said by-passvalve means are automatically opened to admit compressed air to thehammer cylinder in order to retain the hammer piston inactive at oneend, preferably the forward end thereof as above described.

In order that the nature of the inventionmay be more readily understood,the same will now bedescribed, by way of example, as appliedto apneumatically operated percussive hammer for rock drilling and likeboring purposes and of the kind specified, such hammer being describedwith reference to the accompanying drawings in which:

FIGURE 1 shows mainly in axial section the upper part i and 24communicating at their lower ends with radial inlet ports located in thelower part of the said liner, and at their upper ends with lateralportions of the ports 10 leading from the valve chest 3v secured in theupper portion of the hammer cylinder between the liner 22 and th tubularshock-absorber case 14.

The upper end 26 of the shock absorber piston 13 is screw-threaded toscrew into the lower part of an adaptor 27 for connection to the lowerend of the drill tube 19. An internally splined shock absorber bush 28is screwed into the upper end of the shock absorber case 14- and theshock absorber piston 13 (which is corresponding splined) has its upperpart passing through a fluid-tight seal 29 in the upper end of thisbush. The splines of the shock absorber piston in co-operation withthose in the shock absorber bush 28 serve'to ensure that the hammercylinder 1 rotates with the drill tube 19 and also to limit the axialmovement: permitted to the shock absorber piston with the lower part ofthesame hammer as is shown partly in FIGURE 1, the View being insectionon the line IIII in FIG. 3; and FIGURE 3 shows the apparatusof FIG. 2 insection on the line III-III.

In describing this embodiment of the invention and in the claims theapparatus will be regarded as being in such la position that thepneumatic percussive hammer and the drill tube or tubes by which it iscarried occupy a vertical position with the percussive hammer at thelower end i The inner end of applied to opposite ends of the pistonunder ,the control 1- of a distributor valve 7 located in a valve chest8 disposed toward that end of the cylinder 1 remote from the chuck 2,said distributor valve controlling outlet p0rts 9 and .10 for supplyingcompressed air to the lower end of 'the piston 6 and another set ofoutlet ports 11 for supplying compressed air to the upper-end ofthe'piston 6, the distributor valve 7 being adapted to close these setsof outlet ports alternately automatically as the said pistonreciprocates in the cylinder of the hammer and opens "exhaust ports 12in turn to the opposite ends of the pistons 6. A tubular shock absorberpiston 13 is provided coaxially in a shock absorber case 14 screwedcoaxially into the upper end of the hammer cylinder 1, the' shockabsorber piston "being axially slidable with respect to the cylinder 1and being located at the opposite end'of the valve chest 8 to the hammerpiston 6 and having port means 15 through which compressed .air may'besupplied to the valve chest 8 through inlet ports 16 in'the lattercontrolled by aicheck valve 17. which is independent of the distributorvalve 7 and which is urged to its closed position by a compressionspring 18 within the valve chest, said shock absorbed'piston 13 beingadapted, when thehammer is in use, for attachment to the leading end ofadrill tube 19 or string of such drill tubes by which the hammer iscarried and the upper end of which tube 'j or tubes is connected to ahammer rotating motor (not,

shown) mounted on'a catriagefor vertical adjustment respect to its case;and consequently with respect to the hamrner cylinder and valve chest.

At its lowenerid, the shock absorber piston is of reduced diameter-so asto provide a coaxial cylindrical plunger'valve which constitutes themale part of a by-pass valve. The aforementioned ports 15 of the shockabsorber piston lead from the bore 31 of the latter and 'divergedownwardly, the arrangement thus being such 'tween them a centraLcavity32 and the hereinbefore mentioned ports 9, 10, 11 and .16 and the upperand lower ends of the chest are respectively furnished with a centralcoaxial ,bore 33 and a'coaxial bypass bore 34 in whichbores. the plungervalve .30 on the; shock absorber piston is a close sliding fit' and thelower of these bores constituting ,a valve seat for the plunger valvewhich is fluid-tightly sealed inthe central 'bore 33 by a surroundingO-ring 35 or equivalent means.

The ports 16 are arranged as a series around, but

radially spaced from, the central bore 33 in the upper end of the valvechest, the lower ends of the ports 16 being closable by the check valve17 which is of annular form and is slidable upwardly and downwardlyalong that portion of the plunger valve 30 which protrudes I axiallyinto the cavity 32, the spring 18ifor closing this check valvebeingarranged around the said plunger valve and bearing at one'end onthe underside of the check valve and. at the other end upon the bottomof the major cavity 32 of the valve chest. The check valve 17 serves toprevent the reverse flow of air from the through said ports 16. I 7

"When the hammer is operating normally with a revalve chest sultantthrust applied to the bit, the plunger valve- 30 projects into andcloses the central bore 34 in the lower 'end of the valve chest 8.Compressed air passing down the centre of the shockabsorber piston andthroughthe .ports 15 depresses the check valve 17 and passes into thecavity 32 in the valve chest for distribution alternatelyto the upperand lower ends of the "hammer cylinder. The distributor valve 7 is ofannular formv and coaxial with, the bore 34 of the valve chest 8, thevalve "being free for free rising and falling within the valve chest.

i sure above it exceeding that belowit.

The valve? is adapted to open and close the ports 9 and 10 alternatelywith the ports 11 as the piston 6 rises,

and falls, the compressed air flowing into the hammer cylinder to thespace above the hammer piston head via the ports 11 when the distributor-valve is raised due to the pressure below the valve exceeding thatabove it, and flowing into the hammer cylinder below the hammer pistonhead through the ports 9 and 19, when the distributor valve moves'to itslower position on the air pres- As above explained the ports 10communicate, via the aforementioned passages 2 3 and 24 in the liner 22of the cylinder, with series of radialinlet ports25 at: the lowerpartofthe liner 22 and which serve to admit air to the interior of theliner below the lower end of the hammer piston 6.

It will be appreciated 'th'at compressed air is alternately admitted toopposite ends of the piston so that the piston rises and-fall s in rapidsuccession, the lower end of the shank 20 of the piston striking theupper end of the shank 3 of the bit 4 of the hammer each time the pistondescends;

In the cylinder liner are arranged ports 12 connected by ducts 12"through which air in the hammer cylinder is exhausted from the cylinderrespectively towards the end of the downward and upward strokes of thehammer piston, this exhaust air being conducted through axial channels12 in the walls of the hammer cylinder from the ducts 12", the channelscommunicating with an annular space 35' around the piston shank guidebush 21 and along longitudinal channels 36 in the outer wall of V thelatter, down the interior of the bit chuck 2, and down the bit and viachannels through an internally splined chuck bush 37 screwed into'thelowerend of the bit chuck 2. This chuck bush 37 retains the split ringin-positionin the latter as well as co-operating with the splines 38along the bit shank 3. t

Should the shock absorber piston 13 by withdrawn with respect to thehammer cylinder, 'e.g. by the shock absorber 1 piston being raisedthedrill tube or tubes 19 or by" reason of the hammer-entering a cavityduring drilling and falling withrelation to-the shock absorber piston,-

the plunger valve '30 on the shock absorber piston will be withdrawnfrom its .valve seat or bore 34 in the lower end of the valve chest sothat therdistributor valve 7 .will be, as it were, shortcircuited sothat compressed air will then be permitted free flow from the majorcavity 32 of the valve chest 8 directly into the upper end of the hammercylinder efiectively to hold the hammer piston down in its lowerposition and vto stop it reciproeating, only a relatively restrictedflow of compressed air being permitted in theseconditions through theexhaust ports 12 for discharge at-the operating endof the hammer formaintaining debris evacuation at the bit and for preventing the suckingof such debris, sludge or the like into thehammer. I V a It willbeappreciated that even with the movement of the hammer piston arrestedas above described a sufiicient flow of airto the vicinity of theoperating end of the hammer will be available'to maintain the bit of the hammer clear of debris in normal conditions and so prevent theblocking of the operation of the hammer tube means for limited movementrelative to said drill tube means in the direction of said axis, saidhammer cylinder means defining therein a cavity elongated in saiddirection and carrying drill bit means, said drill tube means and hammercylinder 7 means constituting the support members of said apparatus; I

(c) hammer means in said cavityand dividing the same into twolongitudinal portions, said hammer meansbeing reciprocable in saidcavity in saiddirection for actuating'movement of said drill bit meansaway from said drill tube means in said direction; (4'') a-source offluid under pressure; (e) distributor valve means secured to one of saidsupport members and. formed with an inlet conduit-communicating withsaid source, and with two outlet conduits respectivelycommunicating withsaid por-,

'tionsof said cavity, said valve means being respon- 5 sive to pressuredifferencesin said conduits for alter-V natingly connecting said inletconduit with a re'spective outlet conduit; g,

(f) by-pass valve, meanscommunicating with said inlet conduit and one ofsaid outlet conduits, said by-pass valve means including two membersrespectively a connected to said support members for joint movev menttherewith toward and away-from an open position of said by-pass valvemeans members in which said by-pass valve means connects said inletconduit 'cludes' a chuck adapted to receive and retain a bit, saidreciprocable hammer means includes a piston arranged for striking a bitreceived by said shanlc said hammer cylinder means includes a valvechest'above said piston,

said distributor valve means being mounted in said valve chest andadapted to control the admission of saidifluid 'alternatelyto theupperand lower sidesofsaid pistontto reciprocate the latter, .a shockabsorber piston. located above said valve chest and capable oflimitedaxial movement relativeto said hammer cylinder means, said shockI absorberpiston having passage means for the flow'of said fluidtherethrough, and adaptor means connecting the shock absorber piston'to'said drill tube'm'eans for 'sup porting the hammer and supplying saidfiuidtto the latter, and wherein said by-pass'valve means members areconstituted by said shock absorber piston and'said valve" it chest,

plunger valve. 5

whilst this is not operating and until the plunger valve 3%} is returnedinto the valve seat or bore 34 and the normal operation of the hammer isresumed.

I claim: 7 t

1. A pressure-fluid operated percussive boring, apparatus comprising, incombination 5. Apparatus according to claim 4, wherein said plungervalvecomprises a coaxialreduced extension of said'shock absorber pistonand projecting centrally into said valve chest for axial slidingmovement therein, sealing means around said plunger valve adjacent itsentrance to said valve chest, said by-pass bore portionbeingformedwithan axial bore located in the-end of said valve chest re mote from saidshock, absorber piston and' adapted to sealingly receive saidplungervalve; said axial bore connecting said inlctconduitwith said oneportion of said cavity, and the discharge-of said fluid from said inletconduit tosaid cavity being controlled solely. by, said distributorvalve means when said plunger valve i'srs'ealingly rece ved in saidaxial bore.

6. Apparatus according to claim 3, whereinthe valve chest includes anon-return check valve through which said fluid may pass from saidsourceto said .valve' chest 4. Apparatus according to claim 3 whereinsaid memf bers of said by-pass' valve means include a plunger valve onsaid shock absorber piston and a bypass bore por-f tion of the saidvalve chest" adapted to receive said but which bars the return of fluidto the shock absorber piston.

said cavity for actuating movement of said drill bit means in adirection away fromsaid drill tube means, a source of fluid underpressure communicating with said drill tube means, said drill tube meansand hammer cylinder means constituting the supporting members of saidapparatus, and means for exhausting said cavity; in combination, r

(a) first valve means formed with an inlet conduit and two outletconduits, and responsive to pressure differences in said conduits foralternatingly connecting said inlet conduit with respective outletconduits;

(b) means for securing said first valve means to one of said supportmembers for communication of said inlet conduit with said source, andfor respective communication of said outlet conduits with said portionsof said cavity; Y e

(0) second valve means communicating with said inlet'conduit and one ofsaid outlet conduits, said second valve means having two portionsmovable relative to each other toward and away from a position inwhich'said second valve means connects said inlet conduit to said oneoutlet conduit; and

(d)' means for respectively securing said portions of said second valvemeans to said support members for movement toward and away from saidposition when said hammer cylinder means moves on said drill tube means.

References Cited by the Examiner UNITED STATES PATENTS 2,837,317 6/58Hulshizer Q. 121-10 3,059,619 1 0/62 Beaumont 173-78 BROUGHTON G.DURHAM, Primary Examiner,

IMRL J. ALBRECHT, Examiner.

7. FOR USE IN A PRESSURE FLUID OPERATED PERCUSSIVE BORING APPARATUSINCLUDING DRILL TUBE MEANS, HAMMER CYLINDER MEANS MOUNTED ON SAID DRILLTUBE MEANS FOR LIMITED AXIAL MOVEMENT THEREON, SAID HAMMER CYLINDERMEANS DEFINING A CAVITY THEREIN AND CARRYING DRILL BIT MEANS, HAMMERMEANS IN SAID CAVITY AND DIVIDING THE SAME INTO TWO PORTIONS, SAIDHAMMER MEANS BEING RECIPROCABLE IN SAID CAVITY FOR ACTUATING MOVEMENT OFSAID DRILL BIT MEANS IN A DIRECTION AWAY FROM SAID DRILL TUBE MEANS, ASOURCE OF FLUID UNDER PRESSURE COMMUNICATING WITH SAID DRILL TUBE MEANS,SAID DRILL TUBE MEANS AND HAMMER CYLINDER MEANS CONSTITUTING THESUPPORTING MEMBERS OF SAID APPARATUS, AND MEANS FOR EXHAUSTING SAIDCAVITY; IN COMBINATION, (A) FIRST VALVE MEANS FORMED WITH AN INLETCONDUIT AND TWO OUTLET CONDUITS, AND RESPONSIVE TO PRESSURE DIFFERENCESIN SAID CONDUITS FOR ALTERNATINGLY CONNECTING SAID INLET CONDUIT WITHRESPECT OUTLET CONDUITS; (B) MEANS FOR SECURING SAID FIRST VALVE MEANSTO ONE OF SAID SUPPORTING MEMBERS FOR COMMUNICATING OF SAID INLETCONDUIT WITH SAID SOURCE, AND FOR RESPECTIVE COMMUNICATION OF SAIDOUTLET CONDUITS WITH SAID PORTIONS OF SAID CAVITY;